The artificial sweetener in Diet Pepsi, aspartame, will be changed to two others, sucralose and acesulfame, in response to a five percent drop in sales in the United States last year. These artificial sweeteners have all been called safe by the Food and Drug Administration, but Pepsi apparently believes that customer concerns about aspartame are hurting sales. Diet Coke also contains aspartame, and its sales dropped by more than six percent last year.

Studies on the Safety of Artificial SweetenersAspartame: Several studies show increased tumor growth in rats given dosages of aspartame equivalent to those in humans (European Journal of Oncology, July, 2005;10 and Annals of Oncology, 2004;15:1460-1465). However, more than 100 subsequent studies failed to associate tumors with aspartame. People with a genetic disorder called phenylketonuria should not take it because they lack the ability to break down byproducts of aspartame.Sucralose: Most studies show that it is safe even though an Italian animal study showed an association between sucralose and increased risk for leukemia.Acesulfame: More than 100 studies show it is safe, even though one study shows that it increases insulin secretion which suggests that it could increase risk for weight gain and diabetes (Hormone and Metabolic Research, 1987;19(6):233–238).

All Artificial Sweeteners May Increase Risk for Weight Gain and Diabetes
Artificial sweeteners appear to change the huge colony of bacteria in your intestines to favor the harmful bacteria that increase risk for diabetes and weight gain (Nature, September 17, 2014). Scientists fed 10-week-old mice drinks containing either:
• saccharin (the sweetener in the pink packets of Sweet’N Low),
• sucralose (the yellow packets of Splenda),
• aspartame (the blue packets of Equal),
• table sugar, or
• plain water.
The amount of each given to the mice was equivalent to four diet sodas per day for a human. After one week, the mice fed diet drinks had higher than normal blood sugar levels in response to eating sugar, while those that drank sugared water or plain water did not. Saccharin, aspartame and sucralose are chemically very different from each other, but they all caused the same abnormal rise in blood sugar. A high rise in blood sugar after eating sugar is called “glucose intolerance”, which is a marker for diabetes and increased risk for heart attacks.

The scientists then gave antibiotics (ciprofloxacin/metronidazole or vancomycin) to the mice who had been given artificial sweeteners and found that this prevented the high rises in blood sugar. This implied that changes in the intestinal bacteria had caused the rise in blood sugar because killing the changed bacteria (with the antibiotics) returned the mice to normal.

Then they injected intestinal bacteria from saccharin-drinking mice into mice who had never had saccharin and the mice developed very high blood sugar levels after eating sugar. DNA tests showed that the transplanted bacteria now lived in their intestines and were causing the same high rise in blood sugar that occurred in the artificial-sweetener-fed mice.

Similar Experiments on Humans
The researchers then studied 381 non-diabetic people and found that those who use artificial sweeteners regularly had a high incidence of high blood sugar levels after being fed sugar, and that the bacteria in their intestines were also different from people who did not use artificial sweeteners.

For six days they fed saccharin to seven people who had previously avoided artificial sweeteners, and four of them developed high blood sugar levels. Next they injected bacteria from humans fed saccharin into mice intestines and the mice developed high blood sugar levels after being fed sugar. They showed that the intestines of the artificial-sweetener-fed mice had increased amounts of short-chain fatty acids that are readily absorbed into the bloodstream. This was the first study to show that intestinal bacteria are changed by artificial sweeteners.

How Intestinal Bacteria Can Raise Blood Sugar
Artificial sweeteners and many other carbohydrates in the food that you eat are not absorbed directly from your intestines. However, this study suggests that artificial sweeteners change your gut bacteria and the new bacteria are able to break down non-absorbable chains of sugars and starches into short-chain fatty acids. Short-chain fatty acids are readily absorbed from your colon to provide extra calories from a wide variety of foods that you eat. As you absorb more calories from carbohydrates than you normally do, your blood sugar will rise higher and you are likely to gain weight and to increase your risk for diabetes.

Trillions of bacteria live in your intestines. You have more bacteria in your intestines than you have cells in your body. Research on gut bacteria is probably the hottest area of medical research today, under the umbrella of the huge Human Microbiome Project funded by the U.S. National Institutes of Health (NIH). This study will undoubtedly be followed by hundreds of more detailed experiments to clarify the effects of artificial sweeteners on intestinal bacteria and whether they increase risk for diabetes and obesity.

My Recommendations
More research is needed, but I would not wait for future studies. I recommend avoiding regular use of artificial sweeteners. Drink water or unsweetened beverages and severely limit sugar-sweetened foods, except during prolonged exercise.

About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities.
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